CVE-2026-72381
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk48th percentile - higher than 48% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's ksmbd (SMB server) module. The issue is a race between reading fp->owner.name during durable handle owner comparison and freeing it in the reopen path. An attacker could exploit this to gain unauthorized access or cause a system crash.
Risk Assessment
The vulnerability may lead to kernel memory corruption, potentially enabling privilege escalation or denial of service. Organizations using ksmbd (SMB) are exposed to attacks from the local network.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit 7ce4fc40018d and serialization with fp->f_lock). If updating is not possible, consider disabling the ksmbd module or restricting access to the SMB service.
Other vulnerabilities in Linux kernel
See all- CVE-2026-98164Unknown
In the Linux kernel, KVM x86/mmu's kvm_gfn_is_write_tracked() only checks the supplied memslot, but page tracking is per-address-space and shadow pages are shared across address spaces. With SMM, a GFN can be write-tracked in one address space and appear untracked in another. The fix checks the supplied slot first, then the slot for the other address space, preventing mmu_try_to_unsync_pages() from marking an upper-level shadow page unsync and triggering a BUG in pte_list_remove().
- CVE-2026-98048Unknown
In the Linux kernel's BPF subsystem, mark_fastcall_pattern_for_call() must ensure that a matched "spill; call; fill" instruction series is not interrupted by a jump. Otherwise the rewrite applied by bpf_remove_fastcall_spills_fills() is unsound. The fix records instructions targeted by jumps in insn_aux_data[*].jump_target and uses this flag to stop growing a pattern.
- CVE-2026-98047Unknown
In the Linux kernel's BPF subsystem, in_rbtree_lock_required_cb() only checks the innermost verifier frame, so rbtree callback restrictions disappear in a nested static subprogram call frame. The subprogram can unlock the tree, remove and drop the node being compared, then relock, leading to freed memory being linked into the tree.
- CVE-2026-98046Unknown
In the Linux kernel's BPF subsystem, bpf_btf_find_by_name_kind() returns a new BTF object fd through __btf_new_fd(), which reaches anon_inode_getfd() that can sleep while allocating or expanding the current task fd table. The helper prototype does not set might_sleep, so the verifier allows the helper in non-sleepable contexts such as BPF timer callbacks.
- CVE-2026-98045Unknown
In the Linux kernel, a BPF verifier vulnerability affects stack helpers that may block on filesystem reads (e.g., resolving build IDs) but were not marked as sleepable. The verifier could still allow these helpers from non-sleepable regions such as RCU or preemption-disabled sections.
- CVE-2026-98044Unknown
In the Linux kernel, the BPF verifier mishandled legacy packet-load instructions (BPF_LD_ABS/BPF_LD_IND) reached from callbacks, triggering a verifier bug warning and an -EFAULT on BPF_PROG_LOAD. A privileged program loader could trigger this issue.
- CVE-2026-98043Unknown
In the Linux kernel, the BPF verifier incorrectly inferred that a pointer with an unbounded offset is non-NULL based solely on its type. As a result, a BPF program could pass verification while a NULL pointer dereference occurred at runtime.
- CVE-2026-98042Unknown
In the Linux kernel, the BPF verifier could resurrect a scalar id dropped by collect_linked_regs() because snapshots of compared registers were taken before linked registers were collected. This could lead to range inconsistencies and precision propagation issues.
- CVE-2026-98041High
In the Linux kernel, the BPF verifier incorrectly predicted the outcome of pointer vs zero comparisons in JMP32 instructions, failing to distinguish BPF_JMP from BPF_JMP32 comparisons. This led to incorrect inference that a jump is always taken.
- CVE-2026-98040Unknown
In the Linux kernel, the BPF verifier did not mark the zero register as precise for a register-form NULL check. As a result, one path was pruned and the program could dereference a zero pointer at runtime.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free of fp->owner.name in durable handle owner check Two concurrent SMB2 durable reconnects (DH2C/DHnC) on the same persistent_id race the fp->owner.name compare-read in ksmbd_vfs_compare_durable_owner() against the kfree() in ksmbd_reopen_durable_fd()'s reopen-success path. fp->owner.name is a standalone kstrdup() buffer whose lifetime is independent of the fp refcount, and the two sites share no lock: the compare reads the buffer while the reopen frees it, so the strcmp() can dereference freed memory. Commit 7ce4fc40018d ("ksmbd: fix durable reconnect double-bind race in ksmbd_reopen_durable_fd") made the fp->conn claim atomic under global_ft.lock (closing the owner.name double-free and the ksmbd_file write-UAF), but the compare-read versus reopen-free pair was left unserialized. BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80 Read of size 1 by task kworker strcmp ksmbd_vfs_compare_durable_owner smb2_check_durable_oplock smb2_open Freed by task kworker: kfree ksmbd_reopen_durable_fd smb2_open Allocated by task kworker: kstrdup session_fd_check smb2_session_logoff The buggy address belongs to the cache kmalloc-8 Serialize both sides of the race with fp->f_lock. The global durable file-table lock still protects the durable reconnect claim, but fp->owner.name is per-open state and does not need to block unrelated durable table lookups or reconnects. The teardown is left at its existing location after the reopen-success point so that an __open_id() rollback still retains owner.name for a later legitimate reconnect to verify.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS